This invention relates to mounting brackets, and in particular to a mounting bracket adapted for use with an electric motor. Those skilled in the art will recognize the wide applicability of the bracket of this invention in other related situations where sensor or control elements, for example, are mounted to a primary assembly.
Split phase induction motors find use in many appliances with high volume production. These motors commonly include an auxiliary or start winding wound to have a greater resistance than the main field winding, with the starting winding being physically displaced from the main winding. Such motors frequently utilize a number of switches for selectively controlling a number of circuits. For example, single phase induction motors often employ switches to de-energize the start winding once the motor reaches a predetermined operating speed. Concurrently, the same switch may be utilized to selectively regulate other associated electrical circuits. One common way of effectuating the energization of the start winding in response to a predetermined motor speed is by a centrifugally actuated mechanism, responsive to motor speed, which opens the switch of a winding control switch unit in the circuit of the start winding when the motor attains a desired operating or running speed. Generally, such arrangements utilize a lever arm mounted between the switch and the actuator which is engaged by the actuator to operate the switch.
It is known, in the prior art, to use a separable bracket to mount a switch and associated motor protector to a motor end shield. For example, the U.S. Pat. to Lewis, No. 3,782,669, issued Jan. 1, 1974, discloses a separable bracket adapted to carry both an electrical switch, a lever for operating the switch, and an associated motor protector. In Lewis, the protector is clipped to the bracket unit in a conventional manner. The bracket also is mounted exteriorly of the end shield, so that dimensional variations in the end shield can affect the positioning of the bracket, and more importantly the positioning of the lever utilized to actuate the switch with respect to the actuator, the actuator commonly being mounted on a shaft of the associated rotor assembly for the motor.
As will be appreciated by those skilled in the art, dimensional variations in the axial arrangement of actuator and switch components can affect operating life of the switch adversely. The invention disclosed hereinafter provides an end shield and bracket arrangement which simplifies protector mounting to a dynamoelectric machine by forming the end shield on the switch end of the motor with a channel adapted to receive the protector. The bracket is formed with spring means for biasing the protector in the channel. The channel and spring arrangement simplifies protector mounting techniques and eliminates the need for an independent clip for protector mounting. In addition, the channel enables the protector to be mounted in close proximity to the motor windings so that both heat transfer from and current flow through the windings may be employed to protect the motor. The protector is mounted firmly in position so that external lead wires may be connected to it easily. This facilitates insertion of the protector in the motor electrical circuit, and enables this connection to be automated, if desired. The bracket also is provided with a pair of mounting arms which permit mounting of the bracket to the motor side of the end shield, so that variations in end shield design or manufacture no longer affect the axial dimensions and dimensional tolerances of the switch and lever arm arrangement.
One of the objects of this invention is to provide a low cost mounting assembly for an electrical switch.
Another object of this invention is to provide a mounting assembly having spring means for biasing a motor protector in position against an associated end shield of a dynamoelectric machine.
Another object of this invention is to provide a bracket assembly for a dynamoelectric machine which reduces axial dimension variation between a switch mounted to the bracket and any associated actuator.
Another object of this invention is to provide an improved motor protector mounting structure.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.